1. Field of the Invention
The present invention relates to a device for starting an engine.
2. Related Art
In a known internal combustion engine, in order to start the engine, a crankshaft is first rotated reversely and is then rotated forwardly by a starter motor (see Japanese Unexamined Patent Publications No. 2000-303938 and 7-71350). Specifically, in the engine mentioned above, when the engine must be started, the cranking in the reverse direction is first conducted and the cranking in the forward direction is then conducted. This reduces an amount of torque required to start the engine.
When the cranking is conducted in either the forward or reverse direction, a gas flow is generated in the intake passage, the combustion chamber and the exhaust passage. However, during the stoppage of the engine, a residual gas containing unburned HC (hydrocarbon) may exist in the combustion chamber and the exhaust passage upstream of the catalyst, and unburned HC may be adhered to the walls of the intake passage, the combustion chamber and the exhaust passage upstream of the catalyst. Therefore, when the cranking is conducted, the residual gas containing unburned HC may be discharged outside the engine. Although a catalyst is typically arranged in the exhaust passage, the catalyst is not always activated at the engine start. None of the above documents indicates the above-mentioned problem.